What I liked:

Yoo Ah In and Park Shin Hye were both good in this. I especially liked Yoo Ah In in his solitude at the beginning. Here is a young man that appears to live vicariously through the games on his computer. When everything goes south, he has no idea what to do. The scenes between the two of them were good, especially when they were talking to each other on the walkie talkies.

What I didn't care for:

I don't think this needed to be a series, but I didn't feel we got enough back story of the two main characters, especially her. What's her story?
I really have difficulty with the idea of zombies being smart and fast. Maybe it's from my days of watching The Walking Dead, but this movie gave so much credit to the zombies, like they were smarter than those that weren't infected (maybe that was their intent?).
She made a big deal out of being afraid of heights, but then that went out the window, literally.
What was with the other survivor who helped them? That whole, brief storyline was useless.

If you have a couple of free hours and you like zombie shows, give this one a try. It has more questions than answers, but it's an easy watch.